A night vision device (NVD) is an optoelectronic device that produces an image in low levels in light and various wavelength ranges of the electromagnetic spectrum such as those ranges encompassing radiation of visible and infrared wavelengths. Because the NVD aids an individual to see in the dark, it is suitable for many operations such as, but not limited to, military and law enforcement personnel who could benefit “under the cover of darkness.”
Traditional NVDs employ an analog sensor referred to as an image intensifier tube (IIT) as shown in FIG. 1A. Light energy comprised of photons and found in a small amount of light such as moonlight or starlight may be converted by the IIT into electrical energy comprised of electrons that are then subjected to an electron manipulation process prior to being converted back into photons from which a visible image of a scene is produced. Even if the actual scene is not visible to the naked eye, an image of the scene may nevertheless be visible when a viewer is wearing an NVD employing the IIT.
A recent generation of an NVD employs a digital sensor referred to as Electron Bombarded Active Pixel Sensor (EBAPS®) as shown in FIG. 1B. Similar to the IIT, light energy comprised of photons may be converted by the digital sensor into electrical energy comprised of electrons. Instead of converting the electrons back into photons, an imaging sensor creates digital data representative of the image of the actual scene. Even if the actual scene is not visible to the naked eye, an image of the scene may nevertheless be visible as a digital image when a viewer is wearing an NVD employing the digital sensor.
Although an NVD aids a viewer's ability to see in the dark, an exposure to sudden, intense radiation could affect the viewer's ability to see, even when the NVD is being worn. To compensate for this momentary detrimental effect, electronic features have been developed. For instance, an automatic brightness control has been developed to reduce a voltage applied to a microchannel plate of the IIT to keep a brightness of the IIT within optimal limits, thereby protecting the IIT. Also, a bright-source protection has been developed to reduce a voltage applied to a photocathode found in the IIT to protect the IIT and enhance its life; however, the reduction of the voltage has the negative effect of lowering the light gain and/or resolution.